CH340C
Popular USB-to-UART converter with built-in oscillator, 5V/3.3V IO, up to 2Mbps baud rate
Product Overview
Description
CH340C is the most widely used USB-to-UART converter chip, featuring integrated clock oscillator that eliminates external crystal.
With support for baud rates up to 2Mbps and both 5V/3.3V IO levels, this chip is ideal for adding USB connectivity to microcontrollers and embedded systems.
The chip requires minimal external components and comes with comprehensive driver support for Windows, Linux, and macOS.
Product Series
CH
Primary Application
USB-to-serial adapters
Key Features
- USB 2.0 Full Speed compliant
- Built-in clock oscillator - No crystal is needed
- Supports 5V and 3.3V IO voltage
- Baud rates from 50bps to 2Mbps
- Hardware flow control support
- Modem handshake signals
- 5V tolerant inputs
- Low power consumption
- WHQL certified Windows drivers
Specifications
| Interface | USB 2.0 Full Speed to UART |
|---|---|
| Baud Rate | 50bps to 2Mbps |
| IO Voltage | 5V or 3.3V (selectable) |
| USB Speed | Full Speed (12Mbps) |
| Handshake | RTS, CTS, DTR, DSR, DCD, RI |
| Clock Source | Built-in oscillator (no external crystal) |
| Temperature Range | -40°C to +85°C |
| Package | SOP-16, ESSOP-10, MSOP-10 |
Applications
USB-to-serial adapters
Electronic system design
Microcontroller programming
Industrial automation and control
Industrial control systems
Industrial automation and control
POS terminals
Electronic system design
LED controllers
Industrial automation and control
Smart card readers
Electronic system design
GPS modules
Electronic system design
FAE Expert Insights
"CH340C is my go-to recommendation for USB-to-UART applications. The built-in oscillator is a game-changer - it eliminates the external crystal, reducing BOM cost and PCB space. I've used this chip in dozens of projects from industrial controllers to consumer electronics. The driver support is excellent - plug-and-play on modern Windows and built-in Linux support. The 2Mbps baud rate handles most high-speed serial needs. One tip: always include the 100nF decoupling capacitor close to the chip, and ensure your PCB layout keeps the USB traces short and matched."
Built-in oscillator eliminates external crystal, reducing BOM cost
— David Liu, BeiLuo
Frequently Asked Questions
What is the maximum baud rate of CH340C?
CH340C supports baud rates from 50bps up to 2Mbps. The actual maximum depends on your application requirements and USB host capability. At 2Mbps, ensure your UART device and cable quality can support the speed. The chip uses USB 2.0 Full Speed interface with 12Mbps bandwidth, providing reliable communication at all supported baud rates.
2Mbps supports most high-speed serial applications. For higher speeds, consider USB HS solutions. Contact our FAE team for baud rate selection guidance.
Does CH340C require an external crystal?
No, CH340C has a built-in clock oscillator and does not require an external crystal. This reduces BOM cost and PCB space compared to CH340G which requires external 12MHz crystal. The internal oscillator provides stable clock for USB and UART operation across the full temperature range. This is the main advantage of CH340C over CH340G.
CH340C is recommended for new designs. Use CH340G only if you need external clock source for synchronization. Contact our FAE team for variant selection.
How do I configure CH340C for 3.3V operation?
CH340C IO voltage is determined by the VCC pin voltage. Connect VCC to 3.3V for 3.3V IO operation, or 5V for 5V IO operation. The USB interface operates at standard USB levels regardless of VCC. No external level shifting is needed when connecting to 3.3V microcontrollers. Ensure all IO pins stay within 0V to VCC range.
Connect VCC to your system voltage (3.3V or 5V). IO levels will match VCC. Contact our FAE team for mixed-voltage system design.
What drivers are needed for CH340C?
Windows 10/11 include built-in CH340 drivers and typically install automatically. For older Windows versions, download drivers from QinHeng website. Linux kernel 2.6+ includes built-in driver (usbserial). macOS drivers are available for download. All drivers support virtual COM port mode. Android support available for USB host mode devices.
Modern OS typically auto-install drivers. Download from website if needed. Contact our FAE team for driver integration support.
What is the typical application circuit for CH340C?
Basic CH340C circuit requires: 1) VCC connected to 3.3V or 5V; 2) GND connection; 3) 100nF decoupling capacitor on VCC; 4) USB D+ and D- connected to USB connector; 5) TXD and RXD to UART device; 6) Optional handshake signals (RTS/CTS). No external crystal needed. Keep USB traces short and matched. Reference schematic available in datasheet.
Follow reference schematic in datasheet. Keep decoupling capacitor close to chip. Contact our FAE team for PCB layout review.